Contactor improvements

ABSTRACT

An improved, horizontal, continuous contacting-mixing device utilizing internal circulation and having therewith an impeller, a circulation tube and (usually) an indirect heat exchanging tube bundle; an improved type of horizontal circulating, mixing, reaction vessel or contactor; in a horizontal contactor vessel where the impeller is received in lesser internal diameter shell and circulating tube zones, offsetting the cones of the outer shell and circulation tube downwardly at the impeller end of the vessel, thereby to cure fluid flow deficiencies by removing tee necessity of lifting upwardly into the impeller circulating liquids or fluids; reshaping both the circulation tube and outer shell of a horizontal contactor-type reaction vessel in the transition zone between the lesser internal diameter portions thereof conventionally housing the mixing and driving impeller and the greater internal diameter portions thereof conventionally (usually) including a large indirect heat exchanging tube bundle into an offset cone shaped, or offset frusto-conical configuration.

United States Patent [1 1 Putney et al.

[ Sept. 18, 1973 CONTACTOR IMPROVEMENTS [75] Inventors: David H. Putney; John H. Lindau;

Charles L. West, all of Shawnee Mission, Kans.

[73] Assignee: Stratford Engineering Corporation, Kansas City, Mo.

[22] Filed: Mar. 15, 1972 [21] Appl. No.: 234,827

259/DIG. l8; l65/l08; 23/285, 288 E Primary Examiner-John Petrakes Assistant ExaminerPhilip R. Coe Attorney-Thomas M. Scofield 57 ABSTRACT An improved, horizontal, continuous contactingmixing device utilizing internal circulation and having therewith an impeller, a circulation tube and (usually) an indirect heat exchanging tube bundle; an improved type of horizontal circulating, mixing, reaction vessel or contactor; in a horizontal contactor vessel where the impeller is received in lesser internal diameter shell and circulating tube zones, offsetting the cones of the outer shell and circulation tube downwardly at the impeller end of the vessel, thereby to cure fluid flow deficiencies by removing tee necessity of lifting upwardly into the [56] References Cited impeller circulating liquids or fluids; reshaping both the UNITED STATES PATENTS circulation tube and outer shell of a horizontal contac- 2 774 654 12/1956 Reed 23/285 tor-type reaction vessel in the transition zone between z b 7/1957 x the lesser internal diameter portions thereof conven- 2,979,308 4/1961 Putney 165/108 UX tionally housing the mixing and driving impeller and 3,173,763 3/1965 Mill et 1, 23/285 the greater internal diameter portions thereof conven- 3,284,537 11/1966 Webb 23/285 X tionally (usually) including a large indirect heat ex- 3,523,761 8/1970 Graham 165/108 X changing tube bundle into an offset cone shaped, or

FOREIGN PATENTS OR APPLICATIONS offset frusto-conical configuration.

880,758 9/1971 Canada 259/95 14 Claims, 8 Drawing Figures /0 m [I f; 8 av f A; i A n:-

-. I '7:' AP- m:==r.mng a [0 E a li gllll lh I w /4 A Z. \X 2m Ir J2 v w a i we W Patented Sept. 18, 1973 2 Sheets-Sheet 2 1 CONTACTOR IMPROVEMENTS CONTACTORS (CIRCULATING, MIXING, REACTION VESSELS) Contactors are continuous mixers utilizing internal circulation with an impeller, a circulation tube and (usually) an indirect heat exchange tube bundle.

The basic philosophy of a contactor is to obtain the greatest possible circulation and turbulence of the intemal fluids. Newly input fluids are typically discharged immediately before the impeller, upstream, within the circulating tube. These fluids hit the eye of the impeller and are disbursed in the circulating reaction mix. Thus, a contactor is typically a high volume vessel with a high velocity internal circulation rate.

From a process standpoint, the contactor is a device for carrying out chemical reactions under conditions providing intimate contact between reactants, whether in a single phase or more than one phase. A mixingcirculating impeller provides very high shear and turbulence to bring reactants into intimate contact so that the reaction can occur at a maximum rate. In general, the requirements for efficient reaction include l) temperature control with concurrent removal or addition of reaction heat, (2) intimate contact between the reactants and (3) control of the reaction time. When more than one phase is involved, additional requirements include phase dispersion and a homogeneity of the reaction mix. By proper design of a contactor, these various requirements may be optimized for the particular reaction involved.

Thus, this type of reactor may be readily equipped with heat exchange means for the addition or removal of reaction heat thereby to maintain essentially isothermal conditions throughout the reaction zone. High internal circulation is maintained so that any heat generated or required by the reaction may be compensated by heat exchange and the reaction may be accomplished under isothermal conditions.

As mentioned, the contactor may be used with a number of combinations of phases. Thus, it is effective for reactions taking place in a single liquid phase, and two or more immiscible liquid phases, with a combination of liquid and solid phases, gas-liquid phases, or gasliquid-solid phases. In cases where more than one phase is present in the reaction zone, the impeller accomplishes very complete dispersion of one phase in the other and provides an homogeneous mixture of the phases throughout the reaction zone. In these latter cases, the reaction not only proceeds at the phase boundry and a finely divided dispersion of the discontinuous phase for most of the completion of the reaction.

BASIC ELEMENTS AND OPERATION OF THE CONTACTOR l. The contactor shell serves to contain the reaction mixture.

2. The circulation tube serves to establish an internal flow path in the contactor (down the center of the circulation tube and thereafter throughout the annulus between the circulation tube and the shell).

3. The hydraulic head contains shaft sealing means and any required bearings for the impeller shaft, also incorporating a reversal zone for the flow leaving the impeller (or going to the impeller if the flow is reversed).

4. The impeller efiects mixing and circulation in the contactor.

5. Indirect heat exchanging means containing a heat exchanging medium. Generally shown as a tube bundle for addition or removal of heat absorbed or generated during the reaction. The bundles may be of the U-tube type, bayonet tube or others. Also sometimes used for heat exchange are jacketed shells and jacketed circulation tubes.

In typical operation, the conventional flow path within the contactor, starting from the discharge side of the impeller, is through the reversal area in the hydraulic head, thereafter through the annular space between the circulation tube and the outer shell, thereafter through a reversal area in the opposite end of the contactor, and, finally through the center section of the contactor within the circulation tube back to the impeller. The reactants are normally fed as near as possible to the eye of the impeller so that they are immediately and thoroughly mixed and dispersed into the main body of the reaction mix.

In some circumstances, it may be advantageous to reverse the flow within the contactor, thus going first through the center section within the circulation tube, into a first reversal zone at the end of the circulation tube opposite that containing the impeller and then back through the annular space between the circulation tube and the shell into the hydraulic head, thence into the other side of the impeller. In these instances, the reactants are conventionally fed into the annular space between the shell and circulation tube as near as possible to the impeller.

THE PRIOR ART The instant apparatus and process improves over the following prior art constructions and methods relating to horizontally oriented contacting vessels:

Webb, Jr., U.S. Pat. No. 3,284,537, issued Nov. 8, 1966 for Method Of Charging Reactants Through Concentric Feed Tubes;

H. W. Stratford, U.S. Pat. No. 3,027,243, issued Mar. 27, 1962 for Reaction Vessel With Internal Circulation'Tube And Agitator;

Webb, Jr., U.S. Pat. No. 3,027,242, issued Mar. 27, 1962 for Concentric Injector For CirculatingTube Reactor;

D. H. Putney, U.S. Pat. No. 2,979,308, issued Apr. 1 l, 1961 for Apparatus For Controlling Temperature Change Of Blends Of Fluids Or Fluids In Finely Divided Solids;

H. W. Stratford, U.S. Pat. No. 2,909,634, issued Oct. 20, 1959 for Process And Apparatus For Chemical Reactions;

D. H. Putney, U.S. Pat. No. 2,800,307, issued July 23, 1957 for Apparatus For Controlling Temperature Change DESCRIPTION OF THE INVENTION In the Stralford Engineering Corporation horizontal contactors as seen in the above listed patents comprising substantially standard designs on commercial scales, it is necessary to lift upwardly into the impeller the circulating liquids or fluids from the lower portion of the heat exchange unit or tube bundle (if the circulation is down the tube bundle to the impeller) or same upwardly in the outerannulus (if the circulation in the vessel is in the other direction).

There is evidence in the performance of large contactor type reactors that, in spite of the relatively high circulation velocities maintained throughout the reactor (typically approximately 20 to 25 feet per second through the hydraulic head, 3 to 7 feet per second in the annular space between the shell and the circulating tube and 6 to 8 feet per second around the tubes in the tube bundle) some degree of separation of the elements of a typical alkylation process emulsion occurs, (The emulsion contains (1) sulfuric acid, (2) alkylate and (3) isobutane.). With circulation rates inmoderately large units up to 50,000 gallons per minute, it is impractical to further increase this rate in order to increase velocities. Moreover, there is evidence that the velocities around the upper portion of the tube bundle are greater than in the lower portion of the tube bundle.

In the standard horizontal contactor, olefin feed, isobutane recycle and acid recycle feeds enter the contactor immediately before the impeller through suitable nozzles. After mixing in the impeller, the emulsion thereafter flows through the annular space outside of the circulating tube and then down past the cooling tubes inserted in the opposite end of the circulating tube from the impeller. Take-off of the mixture going to the acid settler may be through a nozzle drawing from the top annular space or the bottom annular space. Samples taken from the top side nozzle show a higher hydrocarbon content than samples taken from the bottom side nozzle. Moreover, inspection of the individual tubes of the tube bundle and experience with leading tubes, indicate that most of the erosioncorrosion of tubes occurs in the upper portion thereof.

Inthe improved construction, the cones of both the outer shell and the circulation tube are offset downwardly so that the fluids moving toward the impeller within the circulation tube have a straight path to the lower side of the impeller or drain directly into same. Therefore, it is unnecessary to lift any of the circulating emulsion into the impeller. This description is true even in the case of reversed circulation in that there is less lift in the annulus upwardly to the impeller. This results in an increase in velocity of the circulating mixture moving from the tube bundle to the impeller in the lower part of the tube bundle which in turn decreases the velocity through the upper portion thereof. Thus it is seen that the velocity of circulation throughout the entire unit tends to equalize.

An object of the invention is to provide improvements in circulating, mixing reaction vessels of the contactor type which typically utilize internal circulation involving an impeller, a circulation tube and (usually) a heat exchange tube bundle.

Another object of the invention is to provide improvements in the shaping and configuration of both the outer shell and the internal circulation tube in circulating mixing reaction vessels of the contactor type operating to cure fluid flow deficiencies which have become evident in very large volume conventional vessels of this type.

Another object of the invention is to provide improved contactor reaction vessel structural configurations directed to the outer shell and concentric circulation tubes therewithin which regularize, equalize and advantageously control the relative velocities of flow both within the annulus between the shell and the circulating tube (both upper and lower portions) and, se-

condly, centrally within the circulation tube, whether or not a tube bundle heat exchanging device is present.

Another object of the invention is to reshape both the circulation tube and outer shell of a contactor reaction vessel in the transition zone between the lesser internal diameter portions thereof which conventionally house the mixing and driving impeller and the larger outer diameter portions thereof which conventionally usually include a large indirect heat exchanging tube bundle, this improvement and modification involving shaping the transition zone, in a horizontal contactor, into an offset cone shape, or ofiset frusto-conical configuration.

Another object of the invention is to remove the necessity from large circulating reaction and mixing vessels of the contactor type, of lifting upwardly into the impeller the circulating liquids or fluids from the lower portion of the heat exchanger or tube bundle (if the circulation is down the tube bundles to the impeller) or same upwardly in the outer annulus (if the circulation in the vessel is in the other direction).

Another object of the invention is to provide, within the circulating tube of an improved contactor type circulating, mixing reaction vessel a novel configuration or geometry wherein the reaction components or inputs into the contactor are so placed as to optimize their mixing with the circulating reaction product within the shell.

Other and further objects of the invention will appear in the course of the following description thereof.

DESCRIPTION OF THE DRAWING In the drawing, which forms a part of the instant specification and are to be read in conjunction therewith, an embodiment of the instant invention is shown and, in the various views, like numerals are employed to indicate like parts.

FIG. 1 is a sectional plan view of the improved contactor-reactor.

FIG. 2 is a side sectional view of the device of FIG. 1, the improved contactor-reactor.

FIG. 3 is a view taken along the lines 3-3 of FIG. 2 in the direction of the arrows.

FIG. 4 is a view taken along the line 4-4 of FIG. in the direction of the arrows.

FIG. 5 is a sectional plan view of a modification of the improved contactor reactor.

FIG. 6 is a side sectional view of the device of FIG.

FIG. 7 is a view taken along the line 77 of FIG. 6 in the direction of the arrows.

FIG. 8 is a view taken along the line 8-8 of FIG. 6 in the direction of the arrows.

BASIC CONTACTOR STRUCTURE Referring to the figures, the structure will be first generally described with respect to parts common to all horizontal contactor-reactors of its class, and, thereafter, the particular improvements comprising the instant invention described.

Referring to the figures, the horizontal contactor reactor therein shown comprises an outer shell generally designated 10, same closed at one end by a tube sheet 11 and at the other end by an hydraulic pumping head 12. Within outer shell 10 there is positioned a circulating tube (generally designated 13) open at both ends for free communication with the space within the outer shell. Heating or cooling elements (generally designated 14) in the form of U-bends made of tubing are rolled into or otherwise attached to tube sheet 11. These elements extend through the open end of circulating tube 13 to the left in FIGS. 1 and 2 and occupy an appreciable portion of the space enclosed by the circulating tube. A tube bundle of alternative form such as those seen in Putney U.S. Pat. No. 2,800,307, supra, may be optionally provided as an alternative to that form shown.

A typical heat exchange channel or cover 15 equipped with a central partition or bafile 16 is provided for distribution of heating or cooling medium to the tubes of tube bundle 14.

A pumping impeller (generally designated 17) is located in the open end of circulating tube 13 at the end thereof opposite that receiving tube bundle l4. Impeller 17 is mounted on shaft 18 rotating in a bearing 19 in pumping head 12, sealed by suitable packing glands. Impeller 17 is driven by any suitable prime mover 20, such as a driving motor, turbine or engine, diagramatically illustrated.

Horizontal nozzles 21 and 22 are provided for feeding components of the blend or mixture into the contactor-reactor. Nozzles 21 and 22 extend both through the outer shell and inner circulating tube whereby to discharge the reaction mixture components immediately in front of (typically on the upstream side) impeller 17. Impeller 17 is thus arranged for taking suction from circulating tube 13 and discharging into hydraulic head 12. Within the latter, the flow of fluid is reversed and directed into the annular space between the outer shell and circulating tube. Nozzle 23 is provided on the outer shell for withdrawing the finished blend of components. A separate drain nozzle24 is provided on the under side of the outer shell to serve in emptying the shell or machine. Heat exchange channel 15 is provided with inlet connection 25 and outlet connection 26 for the heating or cooling exchange medium, whichever is being used.

Other forms of heat exchange apparatus may be used without altering the concept. For example, heat exchange elements can be installed in the annular space between the circulating tube and the outer shell of the exchanger. The heat exchange elements can be in the form of pipe coils, thus eliminating the tube sheet and channel construction. The outer shell may be jacketed for the circulation of heating or cooling medium be-- tween the jacket and outer shell to supplement or replace the tubular or coil elements shown. The circulating tube may likewise be jacketed to give a double wall construction for the circulation of heat transfer fluid therebetween, thus providing a heat exchange medium within the body of the circulating stream.

It is further noted that this is a horizontal contactorreactor with ground level seen at 27 and suitable support members for the shell provided at 28 and 29. (FIG. 2). Straightening vanes to control the direction of fluid flow may be provided within the circulating tube as at 30 around the input nozzles 21 and 22 and at 31 adjacent the impeller. Straightening vanes additionally may be provided within the annulus between the shell and circulating tube in the hydraulic head as at 32 in the uniform diameter portion annulus thereafter at 33, in the eccentric cone portion (to be described) as at 34 and the cylindrical annulus portion therefollowing as at 35.

In this type of apparatus, the impeller picks up the components introduced through the nozzles and causes them to circulate as blend through the annular space between the outer shell and the circulating tube. At the tube sheet end of the vessel, the travel of the flowing stream is reversed and the blend or mixture caused to pass through the interior of the circulating tube, at the same time being brought in heat exchanging relationship with the heat exchange elements.

It should be understood that suitable connections are made to nozzles 21 and 22 and valves provided to control the quantity of feed input elements introduced into the vessel. Suitable sources of supply are also provided and suitable pipe connections thereto. Additionally, connections are made to heat exchange inlets at outlets 25 and 26 and valves provided to control the circulation of the heat exchanging medium into the vessel in desired quantity and at proper circulating rate. The temperature of the heat exchanging medium is governed according to the requirements of the particular fluid which is being tempered. Discharge pipes are in each case connected to outlets 23 and 24 equipped with suitable valves to drain off the fluids when desired.

THE IMPROVED CONTACTOR CONFIGURATION It should be noted that each of the outer shell 10 and the circulating tube 13 therewithin have three parts. First there is a greater internal diameter portion of each, 100 and 13a. These portions are cylindrical, circular in cross section, and comprise and include the greater volume portion of the entire vessel. A second portion of each of the outer shell 10 and circulating tube 13 are designated 10c and 13c, respectively. These are concentric, relatively lesser internal diameter portions, also cylindrical and circular in cross section.

The latter described portions of the circulating tube 13, namely, 13a and 130, are spaced from one another and connected to one another by an eccentric, frustoconical portion 13b. The same is true of the outer shell portions 10a and 10s, namely, they are spaced from one another and connected to one another by an ofiset,

frusto-conical section 10b therebetween. Frustoconical eccentric portions 10b and 13b of the outer shell and circulating tube, respectively, are concentric with one another. (Said otherwise, these are frustums of an eccentric cone.)

The result of the above structure, in the horizontal contacting vessel shown, is that the annulus between the circulating tube and the shell, in the lower or underside portions thereof, has a straight run, the entire length of the shell and the circulation tube. On the other hand, the annulus between the shell and the circulation tube in the upper or overhead portions thereof, angles upwardly, while flaring to a greater internal diameter in the passage from the lesser diameter portions of the shell and circulating tube and 13c) to the greater diameter portions thereof 13a and 10a). Said otherwise, the lower portions of the circulating tube and outer shell, in the entire running length thereof, are substantially straight line and cylindrical, whereby the annulus therebetween is of substantially uniform cross-sectional area with straight line flow therethrough. On the other hand, the overhead or upper portions of the circulating tube and outer shell, in the portions 13b and 10b thereof, respectively, angle outwardly and upwardly, flaring from a lesser internal diameter to a greater same, running from the impeller containing portion circulating tube and shell (10c and 13c) to the greater internal diameter portions thereof (10a and 13a).

Generally speaking, the direction of flow of the fluids being mixed and heat exchanged in the horizontal contacting vessel shown is preferably as shown by the arrows within the circulating tube and the annulus therewithout. This means that fluids flow down the inside of the circulation tube into the eye of the impeller 17. Therefore, it is greatly preferred to provide the fluid input feed lines 2l and 22 so that they discharge into the eye of the impeller precisely or immediately just before the choke point or zone of lesser diameter within the circulation tube portion 13b. This results in optimum contacting and mixing of the fluids or liquid being input into the circulating contents of the reaction vessel.

It will be noted that all of the numbers applied to FIGS. 1-4, inclusive, are reapplied precisely to the same structures in FIGS. 5-8, inclusive, but primed. This is because there is no significant change in construction whatsoever between the two modifications (FIGS. 1-4, inclusive, and FIGS. 5-8, inclusive) except that, in the modification of FIGS. 5-8, inclusive, in vertical section, the underside b of outer shell 10 is somewhat downwardly angled running from the right side of the figure toward the left side as one moves away from impeller 17'. That is, comparing the construction of FIG. 6 to that of FIG. 2, in FIG. 2, the bottom wall of the outer shell 10 is perfectly flat, straight or horizontal.

This is not the case in FIG. 6. On the other hand, it should be noted that the underside of the circulating tube 13, as well as that of 13 in both cases, is straight or horizontal. (In all cases, the improvements here described apply to and relate only to horizontal contactor-type vessels, not vertical same.) However, returning to the downward angling of the lower portion of shell 10, it is noted that such angling or slanting in the zone 10b is considerably less in the lower zone of the of the vessel than it is in the upper zone of the vessel. The reason for this is to minimize phase separation in the annulus 35 In all cases, the form of FIGS. 1-4, inclusive, is most preferred, while the form of FIGS. 5-8, inclusive, is less preferred for the performance and achievements of the objects of the invention. However, in most cases, the major objects of the invention, as previously described, can be accomplished in a vessel of the configuration of FIGS. 5-8, inclusive.

Other than as described, the structure and function of the circulating mixing contactor-type reaction vessel of FIGS. 5-8, inclusive, is the same as previously described with respect to FIGS. 1-4, inclusive.

From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

1. In a mixing device having an outer enclosing shell, a circulating tube positioned within said outer shell and spaced inwardly therefrom both concentrically and longitudinally whereby to provide therebetween a continuous annulus, an impeller positioned within one end of said circulating tube, driving means provided for said impeller, an output product opening in said shell and at least one input flow line for reaction mixture components extending into said shell, both the shell and circulating tube being generally horizontally oriented, the improvement which comprises the shell and circulating tube in first portions thereof being cylindrical and of relatively large inner diameter,

a second portion of each of said shell and circulating tube also being cylindrical, of lesser internal diameter, containing the impeller and spaced from said larger internal diameter portions of the shell and circulating tube, and

connecting portions of said shell and circulating tube between the greater and lesser internal diameter portions thereof of offset frusto-conical construction,

whereby the annulus between the circulation tube and the shell, in the lower portions thereof, has a straight run the length of the shell and the circulation tube and is generally of cylindrical shape,

while the annulus between the shell andthe circulation tube in the upper portions thereof angles upwardly while flaring to a greater internal diameter in passing from the said second portions of the circulating tube and shell to the said first portions thereof.

2. A device as in claim 1 wherein the larger internal diameter portion of the circulating tube receives a heat exchanging tube bundle substantially filling a portion of same.

3. A device as in claim 1 wherein the input flow line for reaction mixture components extends both into said shell and said circulating tube, whereby to discharge substantially at the beginning of the second, lesser internal diameter portion of the circulating tube.

4. An apparatus for reducing the temperature change of a blend of fluids including an elongate casing having a discharge opening,

a hollow open-ended circulating tube positioned axially within the casing and spaced from the interior wall thereof forming an annular passage therewith,

animpeller at one end of the circulating tube for creating a cyclic flow of fluids through said tube and in the annular space surrounding the tube,

a circulating head forming the end of the casing adjacent the impeller,

and at least one fluid input line into the casing, the

improvements which comprise the circulating tube and casing having each at least three concentrically positioned parts including:

first, greater internal diameter sections of concentric cylindrical form,

second, lesser internal diameter portions of concentric cylindrical form, the second portions containing the impeller, and

third, concentric, transitional portions located between the first and second portions of offset, frusto-conical configuration,

the lower portions of the circulating tube and outer shell, in the entire running length thereof substantially straight line and cylindrical, whereby the annulus therebetween is of substantially uniform cross-sectional area with straight line flow therethrough,

the upper third portions thereof outwardly and upwardly angled and flaring from lesser internal diameter to greater running from the impellercontaining portions of the circulating tube and shell to the greater internal diameter portions thereof 5. A device as in claim 4 including a header at the other end of the casing from the impeller and a plurality of relatively small diameter heat exchange tubes connected into said header with all of said tubes extending axially of said casing into the larger internal diameter portion of the circulating tube.

6. A device as in claim 4 wherein the said fluid input line penetrates the casing and the circulation tube with its discharge end within the transition zone of the casing and circulation tube.

7. In a mixing device having an outer enclosing shell, a circulating tube positioned within said outer shell and spaced inwardly therefrom both concentrically and longitudinally whereby to provide therebetween a continuous annulus, an impeller positioned within one end of said circulating tube, driving means provided for said impeller, an output product opening in said shell and at least one input flow line for reaction mixture components extending into said shell, both the shell and circulating tube being generally horizontally oriented, the improvement which comprises the shell and circulating tube in first portions thereof being cylindrical and of relatively large inner diameter,

a second portion of each of said shell and circulating tube also being cylindrical, of lesser internal diameter, containing the impeller and spaced from said larger internal diameter portions of the shell and circulating tube, and

connecting portions of said shell and circulating tube between the greater and lesser internal diameter portions thereof of offset frusto-conical construction, while the annulus between the shell and the circulation tube in the upper portions thereof angles upwardly while flaring to a greater internal diameter to a relatively great extent in passing from the said second portions of the circulating tube and shell to the said first portions thereof, the annulus between the circulation tube and the shell, in the lower portions thereof, in passing from the said second portions of the circulating tube and shell to the said first portions thereof, flaring to a greater internal diameter to a relatively lesser extent as compared to the flare of said upper portions.

8. A device as in claim 7 wherein the larger internal diameter portion of the circulating tube receives a heat exchanging tube bundle substantially filling a portion of same.

9. A device as in claim 7 wherein the input flow line for reaction mixture components extends both into said shell and said circulating tube, whereby to discharge substantially at the beginning of the second, lesser in temal diameter portion of the circulating tube.

10. A device as in claim 7 wherein the lower inner portion of the circulation tube is flat in its entire length.

11. An apparatus for reducing the temperature change of a blend of fluids including an elongate casing having a discharge opening,

a hollow open-ended circulating tube positioned axially within the casing and spaced from the interior wall thereof forming an annular passage therewith,

an impeller at one end of the circulating tube for cre- 1 ating a cyclic flow of fluids through said tube and in the annular space surrounding the tube,

a circulating head forming the end of the casing adjacent the impeller, v

and at least one fluid input line into the casing, the

improvements which comprise the circulating tube and casing having each at least three concentrically positioned parts including:

first, greater internal diameter sections of concentric cylindrical form,

second, lesser internal diameter portions of concentric cylindrical form, the second portions containing the impeller, and

third, concentric, transitional portions located between the first and second portions of offset, frusto-conical configuration,

the uppermost third portions thereof outwardly and upwardly angled and flaring from lesser internal diameter to a greater to a relatively great extent running from the impeller-containing portions of the circulating tube and shell to the greater internal diameter portions thereof,

the lowermost third portions thereof downwardly and outwardly angled and flaring from a lesser internal diameter to a greater to a relatively lesser extent, compared to the flare of said'uppermost portions,

running from the said second to said first portions;

12. Apparatus as in claim 11 wherein the said fluid input line penetrates the casing and the circulation tube with its discharge end within the transition-zone of the casing and circulation tube.

13. Apparatus as in claim 11 including a header at the other end of the casing from the impeller and a plurality of relatively small diameter heat exchange tubes connected into said header with all of said tubes extending axially of said casing into the larger internal di ameter portion of the circulating tube.

14. Apparatus as in claim 11 wherein the lower inner portion of the circulation tube is flat in its entire length. i =l 

1. In a mixing device having an outer enclosing shell, a circulating tube positioned within said outer shell and spaced inwardly therefrom both concentrically and longitudinally whereby to provide therebetween a continuous annulus, an impeller positioned within one end of said circulating tube, driving means provided for said impeller, an output product opening in said shell and at least one input flow line for reaction mixture components extending into said shell, both the shell and circulating tube being generally horizontally oriented, the improvement which comprises the shell and circulating tube in first portions thereof being cylindrical and of relatively large inner diameter, a second portion of each of said shell and circulating tube also being cylindrical, of lesser internal diameter, containing the impeller and spaced from said larger internal diameter portions of the shell and circulating tube, and connecting portions of said shell and circulating tube between the greater and lesser internal diameter portions thereof of offset frusto-conical construction, whereby the annulus between the circulation tube and the shell, in the lower portions thereof, has a straight run the length of the shell and the circulation tube and is generally of cylindrical shape, while the annulus between the shell and the circulation tube in the upper portions thereof angles upwardly while flaring to a greater internal diameter in passing from the said second portions of the circulating tube and shell to the said first portions thereof.
 2. A device as in claim 1 wherein the larger internal diameter portion of the circulating tube receives a heat exchanging tube bundle substantially filling a portion of same.
 3. A device as in claim 1 wherein the input flow line for reaction mixture components extends both into said shell and said circulating tube, whereby to discharge substantially at the beginning of the second, lesser internal diameter portion of the circulating tube.
 4. An apparatus for reducing the temperature change of a blend of fluids including an elongate casing having a discharge opening, a hollow open-ended circulating tubE positioned axially within the casing and spaced from the interior wall thereof forming an annular passage therewith, an impeller at one end of the circulating tube for creating a cyclic flow of fluids through said tube and in the annular space surrounding the tube, a circulating head forming the end of the casing adjacent the impeller, and at least one fluid input line into the casing, the improvements which comprise the circulating tube and casing having each at least three concentrically positioned parts including: first, greater internal diameter sections of concentric cylindrical form, second, lesser internal diameter portions of concentric cylindrical form, the second portions containing the impeller, and third, concentric, transitional portions located between the first and second portions of offset, frusto-conical configuration, the lower portions of the circulating tube and outer shell, in the entire running length thereof substantially straight line and cylindrical, whereby the annulus therebetween is of substantially uniform cross-sectional area with straight line flow therethrough, the upper third portions thereof outwardly and upwardly angled and flaring from lesser internal diameter to greater running from the impeller-containing portions of the circulating tube and shell to the greater internal diameter portions thereof.
 5. A device as in claim 4 including a header at the other end of the casing from the impeller and a plurality of relatively small diameter heat exchange tubes connected into said header with all of said tubes extending axially of said casing into the larger internal diameter portion of the circulating tube.
 6. A device as in claim 4 wherein the said fluid input line penetrates the casing and the circulation tube with its discharge end within the transition zone of the casing and circulation tube.
 7. In a mixing device having an outer enclosing shell, a circulating tube positioned within said outer shell and spaced inwardly therefrom both concentrically and longitudinally whereby to provide therebetween a continuous annulus, an impeller positioned within one end of said circulating tube, driving means provided for said impeller, an output product opening in said shell and at least one input flow line for reaction mixture components extending into said shell, both the shell and circulating tube being generally horizontally oriented, the improvement which comprises the shell and circulating tube in first portions thereof being cylindrical and of relatively large inner diameter, a second portion of each of said shell and circulating tube also being cylindrical, of lesser internal diameter, containing the impeller and spaced from said larger internal diameter portions of the shell and circulating tube, and connecting portions of said shell and circulating tube between the greater and lesser internal diameter portions thereof of offset frusto-conical construction, while the annulus between the shell and the circulation tube in the upper portions thereof angles upwardly while flaring to a greater internal diameter to a relatively great extent in passing from the said second portions of the circulating tube and shell to the said first portions thereof, the annulus between the circulation tube and the shell, in the lower portions thereof, in passing from the said second portions of the circulating tube and shell to the said first portions thereof, flaring to a greater internal diameter to a relatively lesser extent as compared to the flare of said upper portions.
 8. A device as in claim 7 wherein the larger internal diameter portion of the circulating tube receives a heat exchanging tube bundle substantially filling a portion of same.
 9. A device as in claim 7 wherein the input flow line for reaction mixture components extends both into said shell and said circulating tube, whereby to discharge substantially at the beginning of the second, lesser internal diameTer portion of the circulating tube.
 10. A device as in claim 7 wherein the lower inner portion of the circulation tube is flat in its entire length.
 11. An apparatus for reducing the temperature change of a blend of fluids including an elongate casing having a discharge opening, a hollow open-ended circulating tube positioned axially within the casing and spaced from the interior wall thereof forming an annular passage therewith, an impeller at one end of the circulating tube for creating a cyclic flow of fluids through said tube and in the annular space surrounding the tube, a circulating head forming the end of the casing adjacent the impeller, and at least one fluid input line into the casing, the improvements which comprise the circulating tube and casing having each at least three concentrically positioned parts including: first, greater internal diameter sections of concentric cylindrical form, second, lesser internal diameter portions of concentric cylindrical form, the second portions containing the impeller, and third, concentric, transitional portions located between the first and second portions of offset, frusto-conical configuration, the uppermost third portions thereof outwardly and upwardly angled and flaring from lesser internal diameter to a greater to a relatively great extent running from the impeller-containing portions of the circulating tube and shell to the greater internal diameter portions thereof, the lowermost third portions thereof downwardly and outwardly angled and flaring from a lesser internal diameter to a greater to a relatively lesser extent, compared to the flare of said uppermost portions, running from the said second to said first portions.
 12. Apparatus as in claim 11 wherein the said fluid input line penetrates the casing and the circulation tube with its discharge end within the transition zone of the casing and circulation tube.
 13. Apparatus as in claim 11 including a header at the other end of the casing from the impeller and a plurality of relatively small diameter heat exchange tubes connected into said header with all of said tubes extending axially of said casing into the larger internal diameter portion of the circulating tube.
 14. Apparatus as in claim 11 wherein the lower inner portion of the circulation tube is flat in its entire length. 